Some machines, such as an elevator system, include a safety system to stop the machine when it moves at excessive speeds or accelerations. In some systems, optical sensing devices may be used to determine the speed of the system. In some elevator systems, dust and debris within the hoistway may obstruct the optical sensor; potentially causing inaccurate readings by the sensing device. There is therefore a need for a means to remove dust and debris from the optical sensing device to maintain proper operation.